The present invention relates to a mixhead for mixing at least two plastic-forming, free-flowing reaction components. The mixhead broadly consists of a housing with feed lines and a bore passing through the housing, in which bore an insert containing a mixing chamber and an outlet channel and inlet openings is arranged exchangeably, as known from U.S. Pat. No. 3,263,928, but without ejector piston.
The so-called double conveyor belt installations for manufacturing sandwich elements with a hard foam core, and, occasionally, continuously operating block foaming installations, are equipped with mixheads which oscillate over the foam breadth and which at the same time apply a reaction mixture to a travelling substrate. Such oscillating mixheads must be as light as possible, because considerable delay and acceleration forces occur at the turning points. The larger the mass to be moved, the greater the wear on the oscillator. Such light mixheads must be rinsed, which is generally carried out with the polyol components in the manufacture of polyurethane foam for example. But this places a burden on the environment, and uses up polyol, which also has to be disposed of due to the contamination it causes. It would be preferable t use self-cleaning mixheads (U.S. Pat. No. 3,263,928, DE-A1-2,920,388, DE-A1-3,017,950), i.e. ones with ejector pistons, such as those which have been accepted in practice for foaming in situ. But these are substantially heavier and therefore not under consideration due to the increased wear they place on the oscillator.
The object of the present invention was to find a mixhead for the application indicated, which is on the one hand light, in order to keep the mass to be moved and hence the amount of wear to a minimum, and which on the other hand does not have to be rinsed when production is interrupted.